Meclizine

Meclizine

Clinical data
MedlinePlus	a682548
Pregnancy category	US: B (No risk in non-human studies)
Routes of administration	Oral, sublingual/buccal
ATC code	R06AE05 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) CA: OTC US: OTC
Pharmacokinetic data
Metabolism	hepatic
Biological half-life	6 hours
Identifiers
IUPAC name (RS)-1-[(4-chlorophenyl)(phenyl)methyl]-4-(3-methylbenzyl)piperazine
CAS Number	569-65-3 Y
PubChem (CID)	4034
IUPHAR/BPS	2757
DrugBank	DB00737 N
ChemSpider	3894 Y
UNII	3L5TQ84570 Y
ChEMBL	CHEMBL1623 N
ECHA InfoCard	100.008.477
Chemical and physical data
Formula	C25H27ClN2
Molar mass	390.948 g/mol
3D model (Jmol)	Interactive image
Boiling point	230 °C (446 °F)
SMILES Clc1ccc(cc1)C(c2ccccc2)N3CCN(CC3)Cc4cccc(c4)C
InChI InChI=1S/C25H27ClN2/c1-20-6-5-7-21(18-20)19-27-14-16-28(17-15-27)25(22-8-3-2-4-9-22)23-10-12-24(26)13-11-23/h2-13,18,25H,14-17,19H2,1H3 Y Key:OCJYIGYOJCODJL-UHFFFAOYSA-N Y
NY (what is this?)

Meclizine (INN, or meclozine) is an antihistamine considered to be an antiemetic. It is sold under the brand names Bonine, Bonamine, Antivert, Postafen, Sea Legs, and Dramamine II (Less Drowsy Formulation). Emesafene is a combination of meclizine (1/3) and pyridoxine (2/3). In Canada, Antivert Tab (which is no longer available) was a combination of meclizine and nicotinic acid.

Meclizine is a first-generation antihistamine (nonselective H₁ antagonist) of the piperazine class. It is structurally and pharmacologically similar to buclizine, cyclizine, and hydroxyzine, but has a shorter half-life of six hours compared to cyclizine and hydroxyzine with about 20 hours (though half-life should not be confused with duration). It is used as an antivertigo/antiemetic agent, specifically in the prevention and treatment of nausea, vomiting, and dizziness associated with motion sickness. Meclizine is sometimes combined with opioids, especially ones of the open-chain class like methadone, dextropropoxyphene, and dipipanone (originally combined with meclizine's parent drug cyclizine, the brand name of this combination is Diconal).

Meclizine is an antagonist at H₁ receptors. It possesses anticholinergic, central nervous system depressant, and local anesthetic effects. Its antiemetic and antivertigo effects are not fully understood, but its central anticholinergic properties are partially responsible. The drug depresses labyrinth excitability and vestibular stimulation, and it may affect the medullary chemoreceptor trigger zone. Meclizine also is a dopamine antagonist at D1-like and D2-like receptors, but does not cause catalepsy in mice, perhaps because of its anticholinergic activity.